1. Field of the Invention
This invention relates to improvements in a brake device for use with shutters in cameras.
2. Description of the Prior Art
In general it is desirable that the shutter curtain run down at as fast a speed as possible. But, the increase in the running speed called for merely by strengthening the driving power on the shutter curtain will give rise to the disadvantage that the shutter curtain is caused to vibrate or bounce by its inertia at the end of its running down movement. To avoid this, a brake device must be provided for slowing down the running shutter curtain from the time just before the running down movement of the shutter curtain is terminated. Such brake device for the shutter conventionally takes the form shown in FIG. 1, where on a brake shaft 1 for the front, or rear shutter curtain there are mounted a pivotal member 2, a frictional member 3 and a pressing member 4, and these members 2, 3 and 4 are secured to a base plate 7 through a spring 5 by a nut 6. The pressing member 4 is anchored at its bent-off portion 4a to the base plate 7. When the driving or master gear 8 of the shutter curtain rotates in a direction indicated by an arrow, a pin 8a planted on the upper surface of the master gear 8 comes to abut on the pivotal member 2 at one end 2a thereof, and the pivotal member 2 is then rotated while the frictional member 3 applies a load thereon. During this time, a spring 9 also applies a braking force to the pivotal member 2. Thus, the combined action of the frictional member 3 and the spring 9 slows down the master gear 8 and brings it to rest. The pivotal member 2 has another arm 2b with an electrical insulator band fixedly secured thereto and serves as an actuator for a synchro contact (not shown).
Since the conventional brake device requires a large number of members mounted on a common shaft as will be seen from the above, it becomes complicated in design and increases the number of steps in the fabricating process which in turn calls for an increase in the production cost.
It is an object of the present invention to overcome the above-described drawbacks and to provide a brake device for use with a shutter having a driving member which device includes a pivotal brake member arranged to engage with the shutter driving member as it runs down and which brake member is mounted on a stationary shaft, whereby at least one of the brake member and the stationary shaft is made of an elastic material to apply a torsional friction force to the pivotal member, and this friction force is made to contribute to the braking of the shutter driving member.
Another object of the present invention is to provide a brake device of the character described above in which at least one of the brake member and the stationary shaft is provided with a spring for adjusting the friction force to a desired value.